CHEMICAL HISTORY OF GENTIAN ROOT. 
341 
that gentianin sublimes without residue at a moderate heat. 
I have always witnessed the contrary — that it could not be 
made to sublime without decomposing a large portion. He 
also announces that this substance decomposes alkaline car- 
bonates. I, on the contrary, have seen carbonic acid decom- 
pose the gentisates and separate the acid in a pulverulent form. 
If an excess of gentisin is boiled in a solution of very pure 
carbonate of potassa, and the gaseous product passed through 
lime water, carbonate of lime is not formed, and the gentisin 
preserves its pale colour, which is a proof that it has not 
entered into combination with the potassa. 
Glue of Gentian. 
This differs from ordinary glue, in its colour, fusibility, 
odour, and composition. The glue of gentian has a soft con- 
sistence, is very tenacious, has a yellow, sometimes a greenish, 
colour; its smell is feeble, and is analogous to that of gentian; 
it has no taste; when heated, it softens at 40°, and melts at 
50°. It is insoluble in water, and in alcohol at 30°. It dissolves 
well in the oils, essence of turpentine, and ether. If treated 
with boiling alcohol, at 40°, it is partly dissolved, letting fall, 
upon cooling, a white, fatty, sticky substance, which appears 
to be formed of a waxlike substance and a green oil. The 
solution retains only the green oil. By treating several times, 
with alcohol at 40°, the glue which had not been dissolved by 
the first treatment, the alcohol becomes charged with new 
quantities of oil and wax. If the residuum be acted upon by 
absolute alcohol, a large proportion of this product is still re- 
moved, which is precipitated by cooling. This deposit is 
white, pulverulent, no longer adheres to the fingers, and ap- 
pears to be almost pure wax. Finally, the substance which 
cannot be dissolved in alcohol, is dissolved in pure ether, 
which, when evaporated, leaves a brown, elastic product, non- 
adherent to the fingers, lighter than water, entering into fusion 
at 120°, burning in the flame of a candle, and diffusing the 
smell of caoutchouc. The cereous substance appears to pos- 
sess considerable resemblance to ordinary wax. Heated, it 
VOL. III. NO. IV. 43 
